1. Field of the Invention
The present invention relates to wireless communications, and more particularly to a method for controlling bit rates in consideration of wireless channel environments for transmitting and receiving moving picture encoding data via a wireless communication network.
2. Description of the Related Art
Various digital moving-picture compression technologies for maintaining image quality at a high level while supporting a low data rate on transmitting or storing moving picture signals have been proposed. For example, a Discrete Cosine Transform (DCT) technique or a Motion Compensation (MC) technique are exemplary compression technologies have achieved a relatively high compression rate.
However, during the encoding of the moving picture data, the moving picture data suffers loss of temporal and/or spatial information while passing through predicative encoding, transformation, and quantization processes, and previous data and next data within a bit stream may have a close interrelation by a Variable Length Encoding (VLC).
Therefore, when an error occurs in a transmission channel in transmitting data having this interrelation, it is difficult to restore not only data at the point of time when the error occurs but also data after the occurrence of the error.
Meanwhile, because of the characteristics of a wireless communication network, traffic congestion may occur on a specific channel, or transmission and/or reception bandwidth may be continually varied due to an increase or a decrease in the number of users within an area covered by a wireless base station. In addition, there may exist a circumstance where a data transmitting/receiving apparatus connected to the wireless communication network either moves within an area in which handover may occur, or moves toward a shadow zone incapable of wireless radio wave transmission/reception.
In the case of transmitting encoded moving picture data via a wireless communication network (e.g., in the case of transmitting moving picture data in real-time streaming during encoding), due to the above-described circumstance, a transmitting side for transmitting the moving picture data may have an inferior wireless channel characteristic, or a receiving side may have an inferior wireless channel characteristic even if the transmitting side has a superior wireless channel characteristic. In this case, a moving picture received in a data transmitting/receiving apparatus of the receiving side undergoes significant image quality degradation due to the loss or quality degradation due to a broken image (e.g., image interruption).
In order to solve the above-described problem, there is a need for encoding moving picture data in consideration of channel environments of a wireless communication network, so as to avoid degradation of image quality.